1. Field of the Invention
The present invention relates to a fan and a fan frame thereof, and in particular to a noiseless fan with disposition of sound absorbers requiring limited space, successfully reducing noises during operation.
2. Description of the Related Art
Within the field of heat dissipation of electronic devices, fans are commonly used in computer systems and many electronic products mainly because fans are cheap, reliable and efficient. In early years, fans were valued based upon heat dissipating efficiency, but noise produced by the fans were ignored. However, in an electronic device, most noise is originated from fans. As shown in FIG. 1, a standard fan 1 has a frame 101 covering an impeller 102, and impeller 102 rotates to produce air flows for heat dissipation. However, the wall of the frame 101 is made of rigid materials. When the impeller 102 rotates, the pressure at the wall changes periodically, and then produces steady sounds (or call noises). Further, the higher the frame 101, the louder the noises produced by the fan because the sound wave reflects, diffracts and resonates between the walls of the frame 101.
An improved conventional fan is disclosed in FIG. 2. A conventional computer fan is disposed within the chamber 13 of the housing 10, and a sound-absorbing cotton 23 is disposed in the housing 10 for surrounding the fan. The periphery of the frame 20 of the fan has several holes 24, so that noise produced during operation of the impeller 40 can be absorbed by the sound-absorbing cotton 23 in the chamber 13.
Nevertheless, fans used in electronic production have standard sizes. For example, a fan labeled 80*30 means the length and width are both 80 mm, and the height is 38 mm. If the above method is applied to a standard-sized fan to reduce noises, the size of the fan and the manufacturing cost would increase accordingly. The increase of size makes the fan to be a non-standard sized fan. For users, fans with non-standardized sizes may cause problems when fitted to modulated heat dissipating systems. In other words, the fans applications are limited when applying to standardized computer and electronic systems.